1. Field of the Invention
This invention relates to a surface cleaning apparatus that delivers cleaning liquid to a surface to be cleaned. In one of its aspects, the invention relates to a surface cleaning apparatus that delivers an ionized liquid solution to a surface to be cleaned for enhanced cleaning. In another of its aspects, the invention relates to a method of cleaning a surface.
2. Description of the Related Art
Extractors are well-known devices for deep cleaning carpets and other fabric surfaces, such as upholstery. Most carpet extractors comprise a liquid distribution assembly and a liquid recovery assembly. The liquid distribution assembly typically includes one or more liquid supply tanks for storing a supply of cleaning liquid, a liquid distributor for applying the cleaning liquid to the surface to be cleaned, and a liquid supply conduit for delivering the cleaning liquid from the liquid supply tank to the liquid distributor. An example of an extractor is disclosed in commonly assigned U.S. Pat. No. 6,609,269 to Kasper, which is incorporated herein by reference in its entirety.
Extractors clean carpets and upholstery typically by applying a cleaning solution to the surface, followed by rinsing and drying. While such a process, and the cleaning liquids used therefor, can remove soil and stains, it typically does not sanitize the surface. Microorganisms, molds, and other pathogens can remain after cleaning.
U.S. Application Publication No. 2003/0159233 of Oh discloses a canister-type vacuum cleaner incorporating an apparatus for generating an electrolytic liquid and spraying the electrolytic liquid onto the surface to be cleaned. The electrolytic liquid generator comprises a pair of electrolyte baths containing water and a catalyzer, such as sodium chloride or calcium chloride, each bath incorporating a cathode and an anode. The generated electrolytic liquid comprises sodium hypochlorite (NaClO), also referred to as household chlorine bleach. The electrolytic liquid has the stain removal and anti-microbial properties of chlorine bleach.
Harsh chemicals effective in removing microorganisms can damage the surface. The use of heat to sanitize the surface, while effective, is also problematic. Generating sufficient heat, particularly steam, is difficult in a typical extractor due to competing concerns over the complex apparatus necessary for steam generation while remaining within desired size limitations, safety concerns, and required power consumption. Additionally, maintaining the surface at an elevated temperature for a sufficient period of time for sanitizing would retard the cleaning process since it would be necessary to retain the extractor at a selected location for a period of time sufficient for a sanitation to be completed before moving on to an adjacent area.